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Chairperson:DR. RUBINA YASMIN
ASSOCIATE PROFESSORDEPT. OF ANAESTHESIOLOGY
NIO&H Moderator:
DR. KANIJUN NAHAR QUADIRASSISTANT PROFESSOR
DEPT. OF ANAESTHESIOLOGYNIO&H
Presenter:DR. NAFIZ MAHMOOD
DO STUDENTNIO&H
OCULAR ANAESTHESIA
ANAESTHESIA:
Reversible loss of feeling or sensation, specially the
loss of pain sensation induced to permit to
performance of surgery or other painful procedures.
From the page of History
Born: December 3, 1857
Died: March 21, 1944
Nationality: AustriaFields: Ophthalmology
Known for:
Cocaine (a south american bush ERYTROXYLUM COCA.)as a local anaesthetic in 1884Ophthalmic surgeon work in Vienna
Karl Koller
From the page of History
Born: March 17, 1832
Died: April 30, 1911
Hermann Jakob Knapp
In 1884 used cocaine for retrobulbar block.
van Lint achieved orbicularis akinesia by local injection
From the page of History
General anaesthesia:First used by W.T.G Morton of Boston, USUsed – ETHER at Massachusetts General Hospital on 16th October 1846 to Gilbert Abbott
Types of ocular anaesthesia : General anaesthesia Local anaesthesia
Topical Regional
Peribulbar blockRetrofbulbar blockParabulbar or sub-tenon blockIntracameral blockFacial blockFrontal block
PREFERRED ANAESHETIC TECHNIQUELOCAL ANAESTHESIA:
• Pterygium • Cataract• Surgery for glaucoma• Minor extra-ocular plastic surgery• Keratoplasty • Dacryocystorhinostomy• Minor anterior segment procedures• Refractive surgey • Vitreo-retinal surgery etc
GENERAL ANAESTHESIA:
• Paediatric surgery• Sqint surgery• Major oculoplastic surgery• Orbital trauma repair• Dacryocystorhinostomy• Vitreo-retinal surgery
GENERAL ANAESTHESIAFOR OCULAR SURGERY
INDICATION:1. In children and infant2. Anxious & uncooperative patient3. Mentally retarded adult4. Patient’s preference
OBJECTIVE:5. Analgesia6. Amnesia7. Loss of consciousness8. Adequate skeletal muscle relaxation
Advantages:
I. safe operative environment
II. Complete akinesia
III. Controlled intra-ocular pressure
IV. For bi-lateral surgery
V. Avoiding complications of L/A
PRE- ANAESTHETIC CHECKUPGENERAL:
• Nutritional status• Retarded growth• Anaemia• Jaundice• Cough• Temperature• Oedema• History of convulsion
RESPIRATORY SYSTEM :
• Cyanosis • Dyspnoea• Auscultation of lung field
AIRWAY:
• Mouth opening• Neck movement• Dentition
CARDIOVASCULAR SYSTEM :• Pulse • Blood pressure• Heart sound (auscultation)• Dependent oedema
INVESTIGATIONSFull blood countUrine analysisStool R/EChest X-ray
Over 40 yearsBlood glucoseECGBlood urea S.Creatinine
OTHER INVESTIGATIONS: S. electrolytes Liver function test Coagulation screening
Echocardiogram – specially for congenital heart disease(valvular disease) also for adult – if indicated
Procedure of General Anaesthesia
1) Pre-medication for anaesthesia
2) Induction & intubation
3) Maintenance & Monitoring
4) Extubation and Recovery
Drugs used in G/A1. Pre-medication for anaesthesia with
• Benzodiazepines (diazepam) –for sedation and reduce
anxiety
• Anti-emetics – metaclorpramide , ondansetron
• Atropine - prevent bradycardia
reduce bronchial and salivary secretion
• Medication for selective patients - hypertensive ,
diabetic , coronary artery disease
2.InductionThiopentone ( thiopental sodium) – 5 mg/kgPropofol – 2.5 mg/kg
3. Maintenance• Muscle relaxants – suxamethonium, vecuronium
etc
• anaesthetic gas – nitrous oxide (N2O) with O2
and Halothene , isoflurane etc.
4. Recovery• Neostigmine • Atropine
• Intravenous agent – pethidine , Fentanyl , NSAID(for pain reduction)
COMPLICATION of G/A• Hypoxia
• Laryngospasm
• Respiratory depression
• Aspiration pneumonitis
• Cardiac arrythmia
• Hypotension / Hypertension
• Convulsion
• Restlessness
EFFECTS OF ANAESTHETIC AGENTS ON IOP
DRUGS EFFECT ON IOP
INHALED ANAESTHETICSVolatile agentsNitrous oxide
Intravenous agentsBarbituratesBenzodiazepinesKetamineOpioids
MUSCLE RELAXENTDepolarizers (succinylcholine)Non- depolarizers
LOCAL ANAESTHESIA
ADVANTAGES: Patient is conscious and alert
Drugs used in G/A can be avoided
Systemic complication is less – Post-operative confusion
Nausea , Vomiting
Urinary retention
Stress response to
cardiac patient
acts by producing reversible block to the transmission of peripheral nerve impulses
DISADVANTAGES:
• Painful
• Difficult in uncooperative patients
NOT SUITABLE FOR:
• Young patient• Mentally unstable patient• Patient with physical disabilities that prevent lying
DESIRED PROPERTIES OF L/A1. Non-irritating , safe and painless2. Must be water soluable3. Rapid onset of action4. Duration of action appropriate to the operation to be
performed5. Non-toxic6. No local after effects ( nerve damage , necrosis)7. Must be effective regardless its application to tissue or
mucous membrane8. Quickly block motor and sensory nerves
LOCAL ANAESTHESIA
Na chann
el
LAH+ (ionised drug)
LA(free base)
LA(free base) LAH+
(ionised drug)
NERVE AXON MEMBRANE
ACTION OF LA
MECHANISM OF ACTION OF L/A
Binds with protein of Na+ channels (at interior side)
Block voltage dependent Na+ conductance ( prevent Na+ influx)
Block depolarization
Initiation and propagation of action potential fails
Afferent impulses can not go to higher center
No pain sensation
Patient preparation for LA
As for GA
Optimal health condition
Friendly rapport
A suitable vein should always be cannulated in all
patient
Full cardio-pulmonary resuscitation equipment
Appropriate monitoring
Toxicity of LA:• Light headedness• Numbness or tingling of circumoral area• Anxious• Drowsy• Tinnitus • Convulsion ( To prevent- Diazepam or TPS)• Coma & apnoea develop subsequently (O2)• Cardiovascular collapse may result due to myocardial depression & vasodilatation
HYPOXAEMIA APNOEA
Types of LA According to chemical structure
Ester group Amide groupProcaineCocaineTetracainebenzocaine
LidocaineBupivacaineRopivacaine
mepivacaine
Esters may cause more allergies
COMMONLY USED L/A
L/A Onset of action
Duration of action
Use (concentratio
n)Oxybuprocai
ne6-20 sec 15 min Topical
(0.4%)
Lignocaine
5-10 min
10- 35 sec
30-60 min
15-20 min
Infiltration (1%,2%,4%)
Topical (4%)
Bupivacaine Moderate 75-90 min Infiltration (0.25-0.75%)
OTHERS
L/A Onset of action
Duration of action
Use (concentratio
n)
Proparacaine
15-30 sec 15-20 min Topical (0.5%)
Amethocaine
10-25 sec 10-20 min Topical (0.5-1%)
Ropivacaine Moderate 1.5-6hrs Infiltration (1%)
TOPICAL ANAESTHESIA
ADVANTAGES: Cost effective Immediate visual recovery Avoidance of complication - globe rupture , nerve
damageDISADVANTAGES:
No akinesia Not suitable for extended surgery Well informed and motivated patient is required
ADVERSE EFFECT OF TOPICAL ANAESTHESIA
• Epithelial and Endothelial toxicity
• Allergy to drug
• Alteration of lacrimation
• Surface keratopathy
USES OF TOPICAL ANAESTHESIA
• Manipulation of superficial cornea and
conjunctiva
• Phacoemulsification in cooperative
patient
• Prior to regional blocks
PERIBULBAR BLOCKMost popular now a days
AIM:Injected into peribulbar spaceSpreads to lid and other spacesProduces globe and orbicularis akinesia and anaesthesia.
L/A agent :o Lignocaine 2%o Bupivacaine 0.75%
Along witho Hyaluronidase 5-7.5 IU/mlo Adranaline 1: 200,000
VOLUME :
8-10 ml (approximately)
INSERTION POINT:• 1st - Junction of medial 2/3rd and lateral 1/3rd of lower
lid adjacent & Parallel to orbital floor • 2nd - Just infero-medial to supra orbital notch or just
medial to medial canthus
POSITION OF PATIENT: Supine and in primary gaze
USE OF PERIBULBAR BLOCK
1. Cataract
2. Glaucoma
3. Keratoplasty
4. Vitreoretinal surgery
5. Strabismus surgery
ADVANTAGES:• Less chance of globe injury• Less chance of optic nerve damage
DISADVANTAGES:• Pain• Conjunctival chemosis• Less akinesia than retrobulbar block
RETROBULBAR BLOCKAIM: Injected in muscle cone to block
• Cilliar nerve and ganglion• 3rd , 4th & 6th cranial nerves • provides - akinesia and anaesthesia of the globe.
POSITION OF PATIENT: Supine and in primary gaze
SITE OF INJECTION:
In the lower lid margin just above a point between medial 2/3rd & lateral 1/3rd of lower orbital margin
DIRECTION OF NEEDLE: backward , upwards and medially towards apex of orbit
VOLUME: 2 – 4 ml usually
ADVANTAGES:• Complete akinesia• Dilatation of pupil• Adequate and quicker anaesthesia• Minimal amount of agent required
Complications :
Retrobulbar haemorrhage
Globe penetration
Optic nerve sheath injury
Optic nerve atrophy
Decrease visual acuity
Retinal vascular occlusion
Cont… Brain stem anaesthesia
Frank convulsion
Extra ocular muscle palsy
Trigeminal nerve block
Oculo-cardiac reflex
Respiratory arrest
Contraindication :
• Bleeding disorder ( risk of retrobulbar haemorrhage)
• Extreme myopia ( globe perforation)
• An open eye injury (may cause expulsion of intraocular
contents)
• Posterior staphyloma
PARABULBAR OR SUB-TENON BLOCK
Conjunctival incision 2-3 mm
Halfway between inf. limbus & fornixto open sub-tenon space
Blunt canulla or needle is inserted to post. Sub-tenon space
Bathing the nerves & muscles within the cone
DRUG : LIGNOCAINE
Dissection
Infiltration
ADVANTAGES:• Avoid vascular and optic nerve injury• Requires lower volume of anaesthetics• Better anaesthesia to iris and ant.segment
DISADVANTAGES:• Subconjunctival haemorrhage• More post-operative morbidity
FRONTAL BLOCKAIM: to block supra-orbital and supra-trochlear nerve supplying the upper lid.
USE: ptosis surgery
SITE OF INSERTION: just below mid-point of supra- orbital margin transcutaneously directed towards roof of orbit
VOLUME: about 2 mlw
INTRACAMERAL ANAESTHESIA
AGENT: lignocain 1% (without preservative or adrenaline)
USE: used for phacoemulsification
FACIAL BLOCK
AIM: blocking the action of orbicularis oculi.
USE : as an adjunct to retrobulbar block.
TYPES:
1. Van lint2. O’Brien3. Nadbath & Rehman4. Atkinson
Major sight and life-threatening complications
A. Retrobulbar orbital haemorrhage
SIGNS & SYMPTOMS
• rapid intraorbital and intraocular pressure elevation• increasing proptosis•marked pain• ecchymoses in the eyelids • Chemosis• vision down to poor perception or no perception of light
MANAGEMENT:
Evaluation: Indirect ophthalmoscopy - for evidence of central retinal artery perfusion compromise.
Immediate medical treatment:intravenous osmotic agents such as – • acetazolamide • mannitol
Surgery: Surgical decompression such as -
• Canthotomy,
• Cantholysis
• Orbital decompression
B. Globe perforation: (Exceptionally soft eye ; myopic eye is more prone)
• Occurred with retrobulbar and peribulbar anaesthesia• suspected if – marked pain during the delivery of local an aesthesia hypotony with inability to secure a stable globe -
intraoperative signs of perforation reduced red reflex due to vitreous haemorrhage Serious sight threatening vitreoretinal complications may
result
**** seek the advice of a specialist vitreoretinal surgeon
C. Nerve InjuryOptic nerve may be damaged by:
●● direct trauma by needle
●● ischaemic damage from intrasheath injection or
haemorrhage
●● pressure from retrobulbar haemorrhage
●● pressure from excess local anaesthetic injection into
the retrobulbar space
●● excessive applied external pressure.
NEED TO CARE :• avoiding deep injections into the orbit and• injecting with the eye in the primary position
D. Brain stem anaesthesiaDue to spread of local anaesthetic along the optic nerve sheath
SYMPTOMS & SIGNS:
• drowsiness
• light-headedness
• confusion
• loss of verbal contact
• cranial nerve palsies • convulsions • respiratory depression or respiratory arrest • cardiac arrest
ONSET OF SYMPTOMS: within 10-20 mins of LA injectionSYMPTOMS LASTS FOR: Hours
E. Muscle palsy
Diplopia and ptosis are common for 24–48 hours post-operatively when large volumes of long-acting local anaesthetics are used.
If this persists or fails to recover, it may be due to muscle damage as a result of :
• intramuscular injection of local anaesthetics• local anaesthetic myotoxicity• ischaemic contracture following haemorrhage/trauma
F. Oculocardiac Reflex (Trigeminovagal reflex)
Trigeminal nerve – afferent and vagal efferent pathway
CAUSES:
• Traction on extra-ocular muscle• Pressure on globe
RESULT: Bradycardia Ventricular ectopy Ventricular fibrilation
AFFERENT PATHWAYImpulses
Long & short cilliary nerve
Cilliary ganglion
Trigeminal gasserian ganglion
main trigeminal sensory nucleusin the floor of the 4th ventricle
EFFERENT PATHWAYCardiovascular center of medulla
Vagus nerve
Heart
LCN
SCN
CG TGG
VN
afferent
efferent
Treatment • Stop the surgical stimulus immediately. • Ensure adequate ventilation . • Ensure sufficient anesthetic depth.
Atropine / Glycopyrrolate (anti-cholinergic): often helpful immediately or prior surgery
TAKE HOME MESSAGES• All local anaesthetic agents are myotoxic• Direct injection into a muscle should be avoided• No LA technique is entirely free of severe systemic adverse events• short, fine needle should be used• the eye in the primary gaze position (looking straight ahead)• Gentle aspiration after insertion of needle should be done to alleviate possible entry to blood vessel.• Bevel of the needle facing the globe and tangenital to sclera.• All occular surgery with LA should be treated as GA.